SYSTEM AND METHOD FOR COMPENSATING ORIENTATION OF A PORTABLE DEVICE

• US 20130151195A1
• Filed: 12/12/2012
• Published: 06/13/2013
• Est. Priority Date: 12/13/2011
• Status: Abandoned Application

• Current Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Marinoni, Alberto
• Application Number:
  US13/712,605
• Publication Number:
  US 20130151195A1
• Time in Patent Office: Days
• US Class Current: 702/151
• CPC Class Codes: G01B 7/30 for measuring angles or tapers; for testing the alignment of axes
• CPC Class Codes: G06F 3/0346 with detection of the device orientation or free movement in a 3D space, e.g. 3D mice, 6-DOF [six degrees of freedom] pointers using gyroscopes, accelerometers or tilt-sensors

Abstract

A system for compensating orientation of a portable device is provided with a processing unit for: determining a roll rotation angle of the portable device in a mobile reference system associated thereto; and applying a rotation matrix, which is a function of the roll rotation angle, for transforming relative displacements of the mobile device in the mobile reference system into corresponding displacements in a fixed reference system, of an inertial type, thus compensating the orientation of the portable device. The processing unit determines the roll rotation angle, in the presence of dynamic acceleration, by means of: acquisition of a roll angular velocity of the portable device by a gyroscopic sensor fixed with respect thereto; and time integration of the same roll angular velocity.

Claims

1. A system comprising:

a portable device;

a processing unit fixed to the portable device, the processing unit configured to;

perform a first processing operation for determining in a first operating condition a roll rotation angle of the portable device, the first processing operation including acquiring a roll angular velocity of the portable device and determining the roll rotation angle by performing a time integration of the roll angular velocity; and

apply a rotation matrix that is a function of the roll rotation angle, the rotation matrix being configured to transform relative displacements of the portable device in a mobile reference system into corresponding displacements in a fixed reference system, of an inertial type, the corresponding inertial displacements being independent of the orientation of the portable device.

2. The system according to claim 1, comprising a gyroscopic sensor fixed with respect to the portable device and configured to detect the roll angular velocity of the portable device and provide a signal indicative of the roll angular velocity to the processing unit.

3. The system according to claim 2, wherein the gyroscopic sensor is a MEMS triaxial sensor.

4. The system according to claim 1, wherein the processing unit is configured to determine a presence of a dynamic acceleration acting on the portable device in addition to gravity acceleration, as the first operating condition in which to perform the first processing operation for the roll rotation angle.

5. The system according to claim 4, wherein the processing unit is further configured to perform a second processing operation for determining the roll rotation angle in a second operating condition that corresponds to a static condition of the portable device, the second processing operation including:

acquiring acceleration components acting on the portable device along three orthogonal axes of the mobile reference system; and

determining a value of the roll rotation angle as a function of the acceleration components.

6. The system according to claim 5, wherein the processing unit is configured to perform the second processing operation for determining an initial value of the roll rotation angle for time integration of the roll angular velocity.

7. The system according to claim 5, further comprising an acceleration sensor fixed with respect to the portable device and configured to detect the acceleration components acting on the portable device.

8. The system according to claim 5, wherein the mobile reference system comprises a longitudinal axis about which the roll angular velocity of the portable device acts in use, and wherein the processing unit is configured to detect the first operating condition when the corresponding displacements of the portable device along a horizontal axis and a vertical axis of the mobile reference system, orthogonal to the longitudinal axis, are not lower than a first threshold, and a resultant of the acceleration components deviates from a reference value more than a second threshold.

9. The system according to claim 8, wherein the processing unit is configured to dynamically set the reference value to a value of the resultant of the acceleration components detected upon occurrence of the second operating condition.

10. The system according to claim 1, further comprising:

a gyroscopic sensor fixed with respect to the portable device and configured to provide to the processing unit a yaw angular velocity and a pitch angular velocity of the portable device; and

wherein the processing unit is further configured to determine the relative displacements of the portable device in the mobile reference system as a function of the yaw and pitch angular velocities.

11. The system according to claim 1, wherein the portable device is a three-dimensional pointer device, and wherein the fixed reference system is associated with a display screen of an electronic apparatus, and the processing unit is configured to carry out corresponding displacements on the display screen as a function of movements of the three-dimensional pointer device.

12. The system according to claim 1, comprising:

a gyroscopic sensor fixed with respect to the portable device and configured to detect the roll angular velocity of the portable device; and

an acceleration sensor fixed with respect to the portable device and configured to detect acceleration components acting on the portable device along three axes of the mobile reference system, wherein the processing unit, the gyroscopic sensor, and the acceleration sensor are housed within a housing of the portable device.

13. A method for compensating for changes in orientation of a portable device, the method comprising:

acquiring a roll angular velocity of the portable device in a mobile reference system associated with the portable device;

determining a roll rotation angle that the portable device rotated by performing a time integration of the roll angular velocity; and

applying a rotation matrix that is a function of the roll rotation angle for transforming relative displacements of the mobile device in the mobile reference system into corresponding displacements in a fixed reference system that is of an inertial type, the corresponding displacements being independent of the orientation of the portable device.

14. The method according to claim 13, comprising determining the presence of a dynamic acceleration acting on the portable device, in addition to a gravity acceleration.

15. The method according to claim 14, wherein determining a roll rotation angle includes performing a first processing operation for determining the roll rotation angle in a first operating condition corresponding to a dynamic condition of the portable device, the method further comprising determining the roll rotation angle in a second operating condition by performing a second operating condition, the second operating condition corresponding to a static condition of the portable device, wherein determining the roll rotation angle in the second operating condition includes:

acquiring acceleration components acting on the portable device along three orthogonal axes of the mobile reference system; and

determining the roll rotation angle as a function of the acceleration components.

16. The method according to claim 15, wherein determining the roll rotation angle in the second operating condition determines an initial value of the roll rotation angle for the time integration of the roll angular velocity.

17. A portable device comprising:

a gyroscope sensor configured to detect a roll angular velocity of the portable device; and

a processing unit coupled to the gyroscope, the processing unit configured to;

receive a signal from the gyroscope indicative of the roll angular velocity of the portable device,

determine a roll rotation angle of which the portable device is rotated by performing an integration of the roll angular velocity, and

transform relative displacements of the mobile device in a mobile reference system into corresponding displacements in a fixed reference system by applying a rotation matrix that is a function of the roll rotation angle, the corresponding displacements being independent of the orientation of the portable device.

18. The portable device according to claim 17, wherein the processing unit is further configured to detect of a dynamic acceleration acting on the portable device in addition to gravity acceleration.

19. The portable device according to claim 17, wherein the fixed reference system is associated with a display screen of an electronic apparatus.

20. The portable device according to claim 17, wherein the gyroscopic sensor is a MEMS triaxial sensor.